So I got the answer for you, no pictures this time, just follow the link to see the Dell Inspiron 15 (1545) Motherboard System Board with Discrete ATI Radeon 4330 Video - H314N - yes, it is soldiered to motherboard and NOT REMOVABLE!!
http://www.parts-people.com/index.php?action=item&id=6183
Compare the pictures, the one I provided previously is missing third heatsink inline with processor - your Discrete video card.
If parts are still available it cost $200, plus you will need to change $$ heatsink, do a lot of work and may be spend more $$ - you would have to change motherboard yourself!
So, if you want to invest $300-400 into old laptop go ahead, or just buy a new one and check what you are buying, so you would not look for the...